A quasi steady state model for flash pyrolysis of biomass in a transported bed reactor

Abstract

In this work a quasi-steady state Lagrange multiphase model for biomass pyrolysis in a transported bed reactor was developed. Using biomass three components and lumped kinetic model and char-gas ratio in the thermochemical conversion of biomass to tar, gas and char. The transported bed reactor operated a batch-continuous operation with both biomass and sand (heat source) as feeder at the top of the reactor, while the volatile products were collected and rapidly condensed. The model developed considered the mass flow of the biomass, hot sand and sweeping gas (Nitrogen) in addition to the complex pyrolysis kinetic mechanism. In simulating the model, the calculation was split into two modular steps. The solid phase module was first solved and the results were consequently used in the gas phase module. The focus of the simulation study was on the yield of tar; with variation in biomass feed rate and temperature. The model predictions consistently showed for all simulations, that temperature above 479.5 °C was for tar production. It further predicted that increase in biomass feed rate does not significantly increase tar. The optimal biomass feed rate was 4.0 g/s which correspond to tar yield of 69.53% and temperature of 480 °C.